The Anatomy and Function of the Semilunar Valves

Abstract

The semilunar valves determine the passage of blood between the ventricles and the main arteries, transporting blood away from the heart to the vital organs. In a healthy individual these valves are defined by three leaflets attached in a semilunar fashion within a supporting sinus making up an arterial root positioned between their respective outflow tracts and arterial trunks. During systole, when the ventricles are contracting, the semilunar valve leaflets open to allow blood to flow to the body, i.e., ventricular ejection. As the myocardium starts to relax, prior to ventricular end diastole, the pressure within the right and left ventricles drops below the pressures in the arterial system causing the valves to snap shut. This chapter covers the histological, structural, and functional features of both the aortic and pulmonic semilunar valves and discusses the use of echocardiography to image the structures. A detailed understanding of the semilunar valve anatomy provides the foundation of knowledge critical to physicians and engineers developing future clinical therapies for the treatment of congenital and degenerative diseases.